Japanese Patent document JP-H6-6-23742 Y2 discloses a conventional starter. This starter includes, as shown in FIG. 3, an output shaft 120 supported by a bearing 100 on a housing 110. The output shaft 120 is free to rotate and slide axially. A one-way clutch 140 transfers torque from a motor 130 to the output shaft 120. A pinion gear 150 is fit to the end of the output shaft 120 with a spline. The output shaft 120 of this starter is moved to the right in FIG. 3 by a shift lever 160 to engage a ring gear of an engine (not shown) through the pinion gear 150.
In the conventional art disclosed in the above document, the pinion gear 150 is attached to the end of the output shaft 120 that protrudes from the bearing 100 toward the outside of the housing 110 (opposite the clutch 140). In this structure, the one-way clutch 140 and the pinion gear 150 are both supported by the bearing 100. This results in an increased distance between the clutch 140 and the pinion gear 150. Furthermore, the axial distance between the end of the pinion gear 150 to the rear end of the motor 130 is increased. This makes it difficult to mount the starter to the engine because of possible interferences between the starter and the accessories and/or wires.
The output shaft 120 is only supported at one end based on the relative position of the bearing 100 and the pinion gear 150. This structure provides less strength compared to a structure having two bearings supporting both ends of the output shaft 120 such that the pinion gear 150 is located between the two bearings.
In view of the above-described problem, one object of the present invention is to provide a better way to mount the starter by decreasing its axial length between the edge of the pinion gear and the rear end of the motor and also reinforcing the output shaft.